dm raid1: set discard_zeroes_data_unsupported
We can't guarantee that REQ_DISCARD on dm-mirror zeroes the data even if the underlying disks support zero on discard. So this patch sets ti->discard_zeroes_data_unsupported. For example, if the mirror is in the process of resynchronizing, it may happen that kcopyd reads a piece of data, then discard is sent on the same area and then kcopyd writes the piece of data to another leg. Consequently, the data is not zeroed. The flag was made available by commit 983c7db3 (dm crypt: always disable discard_zeroes_data). Signed-off-by: NMikulas Patocka <mpatocka@redhat.com> Cc: stable@kernel.org Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
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